Police said the 34-year-old man was attacked on Hall Road near the junction with Stott Terrace in the early hours of Sunday July 4.
Police were called just after 1.30am.
It is believed a disturbance had taken place at the location just beforehand, and that a number of persons were present.
The victim remains in a stable condition in hospital.
Detective Sergeant Andrew Ellis of Bradford District CID, said: “We are continuing to investigate what has clearly been a serious assault on the victim and very much want to hear from anyone who can assist us locate those responsible.
“From our enquiries we believe a number of persons were present at the scene of the attack and ran from it shortly before emergency services were called.
"Anyone who saw persons running away or has mobile phone, CCTV or dashcam footage of them or of the assault itself is asked to contact us.
“Any footage or information which can assist our enquiries can be given to Bradford CID on 101 or online at www.westyorkshire.police.uk/101livechat
“Reports can also be made in complete anonymity to the independent Crimestoppers charity on 0800 555 111.”